Monday, June 14, 2010

Rodent of the Week: How habits are formed

When I was in high school, I had to drive a long distance on a freeway to get to school. After arriving, I often wondered how I got there. I didn't remember the drive or even thinking about driving.

This feeling is a common (and, yes, somewhat scary) experience that a group of neuroscientists think they can better explain. In an experiment with rats, researchers at MIT identified two distinct neural circuits in the brain that show distinct changes when the rats were learning to navigate a maze and, later, after they mastered the task.

The rats were placed in a maze that had chocolate sprinkles at the end. The activity in specific parts of their brains was analyzed as they learned the maze, which included a T-juncture where they had to stop and choose to turn right or left. The rats performed the maze repeatedly until they had learned it.

The study showed that one specific neural circuit became stronger with practice. A second neural circuit showed high activity occurring at times when the rats had to make a decision in the maze. But as they learned the maze, activity in this circuit declined. The task had become habitual.

So, arriving at school in one piece wasn't just a matter of luck. "It is good to know that we can train our brains to develop good habits and avoid bad ones," the lead author of the study, Ann Graybiel, said in a news release.

Understanding how specific regions of the brain change through learning could help in developing new treatments for brain-based diseases. The study was published Thursday in the journal Neuron.